ASC (America's Servicing Company) Wells Fargo owned company Paid large sum to lower principal, new amount added to principal Des Moines Iowa

I called in advance to determine how my Home Equity Loan would be affected by me paying around $85,000 toward the principal.  I asked if there would be an early payment penallty.  The answer was 'no'.   I was current on all my payments.  I sent the $85,000 check, marked 'apply to principal only'.  It was sent 'Certified, Return Receipt Requested'.   The lender received the payment on March 2.  I also sent my monthly payment of $731.28 thru my bank to be delievered March 6 so it would get there after the large principal check, specifically so that my March 6 payment would have more money going toward the principal after the $85,000 was applied to my loan.  I was told by the representative that the $731.28 would have a very small amount (around $90 applied to interest by sending it later than the check of $85,000), thus allowing a higher amount to be applied to my principal from the regular March payment which would not be posted until after the $85,000 had been posted.  A statement I received from the lender shows that ASC posted the $731.28 to my account on March 6 (instead of the date they received it of March 2.....this gave ASC 5 days to post that regular monthy payment to my account but they chose to post it before they posted my $85,000 check which arrived there on March 2.    One representative stated during a call I made on Friday, March 13, that they needed to satisfy my March payment before they could post the $85,000 principal amount to my loan.  On the statement that arrived at my address on Saturday, March 14, they also note that 'the $84,288.72 is unapplied at that time (That check was for $85,000).    What I found out they did with the $85,000.00 check I sent they applied $731.28 to my April payment which isn't even due until April 1 (they have told me the monthly payment has a 10 day grace period).  Before I mailed in the $85,000 check for principal only, I had a balance of $111,344.36, so subtracting the $85,000 from that balance left a balance of $26,344.36.  Subtract the March payment principal payment of approx. $600 from that and the balance should be approximately $25,744.36.   ASC shows a balance of $26,539.83, which is definitely incorrect.   Somewhere in the figures they added $795.44.   That is outrageous and questionable business practices...fraudulent.  By the way, they tried their best to get me to refinance.  Even after I told them definitely no, they have sent 2 refi packages in the mail to me since then.   They even took out a payment for April for $731.28 with the greater amount applied to interest instead of to the principal....after the $85,000.00 was applied!  Imagine that!